Just Went to 33s / Do I Go to 4.30 or 4.56 ?

[WILDHOBO]

I was using extreme examples of stock Jeep configurations, including the JK we used to wheel. I'm not arguing that a 45-1 crawl ratio is optimal at all. But there comes a point where it really doesn't feel all that different in an auto. 85-1 in the stock xr is more than enough for even the steepest climbs or descents even on 39s. I'm not arguing that 3.73s and 40s are a good combo, but I'd rather run that than 4 56s and 33s as regardless of how often I get out and wheel the time driving on the road to get to and from those wheeling trips would be miserable. I've gone to the deep end of gearing more than once and every time it has sucked, although the double overdrive does make it suck less. I love the fact that I can comfortably roadtrip the Jeep at 85mph+ and then run 8+ rated trails when I get there. That is what is so impressive about the modern JL/JT platform. Pretty much every prior Jeep was a compromise where you're gearing limited your top speed to 70mph or you flat didn't have the torque to crawl up steep obstacles at elevation. Thanks to the low 1st gear and double overdrive you can do both with ease. I prefer to shoot for 2k rpms at 75mph. Some prefer 2500 so that the motor is more into its power band. I don't want to be in the power band when cruising around at light loads. Jeep themselves are all over the board with gearing so there could never be a consensus. From my experience and the way I drive I'll post in every thread debating the topic that there is such a thing as gearing too deep and there are drawbacks. In my opinion the benefits are far over stated as well. Having extensively crawled with the stock Rubicon 77-1 and the added 5.38s and 101-1 in the exact same Jeep i can honestly there's little gain. 77 is slow enough to creep up or down anything. Short of 40"+ I'll never go below 4.88s with this trans. Lesson learned the hard and expensive way. With the current xr, going from the 85-1 to 91-1 by dealing to 4.88s would likely not even be noticeable.

I agree with most of that actually. Well said.

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[Zachanadandy]

I agree with most of that actually. Well said.

I just try to balance the voice of those who are convinced the lowest possible gears are the way to go with the neve regear crowd. I find the the sweet spot is more in the middle. Even on 39s the xr still has a lower drive ratio in high range than a stock sport or sahara and thus higher cruising rpms and when paired with the 4-1 transfer case has much better slow speed control and crawl ratio. We won't even go in to the tiny pinion gear when you get into the 5.xx gear ratios on a dana44.

 

[Just Mark]

I just try to balance the voice of those who are convinced the lowest possible gears are the way to go with the neve regear crowd. I find the the sweet spot is more in the middle. Even on 39s the xr still has a lower drive ratio in high range than a stock sport or sahara and thus higher cruising rpms and when paired with the 4-1 transfer case has much better slow speed control and crawl ratio. We won't even go in to the tiny pinion gear when you get into the 5.xx gear ratios on a dana44.

For all those with 5.xx gear ratios, bummer about your tiny pinions. ???

 

[Wheelin98TJ]

I was using extreme examples of stock Jeep configurations, including the JK we used to wheel. I'm not arguing that a 45-1 crawl ratio is optimal at all. But there comes a point where it really doesn't feel all that different in an auto. 85-1 in the stock xr is more than enough for even the steepest climbs or descents even on 39s. I'm not arguing that 3.73s and 40s are a good combo, but I'd rather run that than 4 56s and 33s as regardless of how often I get out and wheel the time driving on the road to get to and from those wheeling trips would be miserable. I've gone to the deep end of gearing more than once and every time it has sucked, although the double overdrive does make it suck less. I love the fact that I can comfortably roadtrip the Jeep at 85mph+ and then run 8+ rated trails when I get there. That is what is so impressive about the modern JL/JT platform. Pretty much every prior Jeep was a compromise where you're gearing limited your top speed to 70mph or you flat didn't have the torque to crawl up steep obstacles at elevation. Thanks to the low 1st gear and double overdrive you can do both with ease. I prefer to shoot for 2k rpms at 75mph. Some prefer 2500 so that the motor is more into its power band. I don't want to be in the power band when cruising around at light loads. Jeep themselves are all over the board with gearing so there could never be a consensus. From my experience and the way I drive I'll post in every thread debating the topic that there is such a thing as gearing too deep and there are drawbacks. In my opinion the benefits are far over stated as well. Having extensively crawled with the stock Rubicon 77-1 and the added 5.38s and 101-1 in the exact same Jeep i can honestly there's little gain. 77 is slow enough to creep up or down anything. Short of 40"+ I'll never go below 4.88s with this trans. Lesson learned the hard and expensive way. With the current xr, going from the 85-1 to 91-1 by dealing to 4.88s would likely not even be noticeable.

I had a 3 speed auto TJ with 4.56 gears as a daily for many years. With both 33” and 35” tires. Many highway trips at 3,500+ RPM. It was a trade off I was willing to accept. Now with the 2 overdrive transmissions, you don’t have to accept that trade off. You can gear deep and still run low RPM on the highway.

 

[Zachanadandy]

I had a 3 speed auto TJ with 4.56 gears as a daily for many years. With both 33” and 35” tires. Many highway trips at 3,500+ RPM. It was a trade off I was willing to accept. Now with the 2 overdrive transmissions, you don’t have to accept that trade off. You can gear deep and still run low RPM on the highway.

With an auto with a 4.7-1 1st gear you are geared deep from the factory though. The TJ had a 2.84 1st gear in the auto. Even if it was a Rubicon you'd need 6.71 axle gears just to match a JL/JT with 4.10s. You thought that TJ was geared low for off road and accepted the trade off as you say... it was the equivalent of running 2.75 axle gears behind the 8 speed. That's my point, there is no trade off with this trans. Your definition of low RPM on the highway and mine clearly differs. I prefer 2k over 2500 and neither of us are lacking in crawl ratio or low speed control. The JTM could use more gear if I was crawling it, but I'd still go for the transfer case gearing over axle gearing personally. This transmission has changed the game. Here's an easy perspective if you had a non-rubicon TJ. Remember the doubler kits they sold back in the day to add a 2nd range box in front of the 231? Even with 2x2.72 low range and 4.10s to retain freeway driveability, that crap trans would leave you with...an 86-1 crawl ratio. With a doubler you'd get a stock XR crawl ratio and still have worse freeway gears. Tell me again I need more gearing? I guarantee the JLUR outcrawls the TJ, 0-60s in half the time, and will roll 85mph without straining and returning double the fuel economy. These aren't the Jeeps of yesterday by a long shot.

 

[Wheelin98TJ]

With an auto with a 4.7-1 1st gear you are geared deep from the factory though. The TJ had a 2.84 1st gear in the auto. Even if it was a Rubicon you'd need 6.71 axle gears just to match a JL/JT with 4.10s. You thought that TJ was geared low for off road and accepted the trade off as you say... it was the equivalent of running 2.75 axle gears behind the 8 speed. That's my point, there is no trade off with this trans. Your definition of low RPM on the highway and mine clearly differs. I prefer 2k over 2500 and neither of us are lacking in crawl ratio or low speed control. The JTM could use more gear if I was crawling it, but I'd still go for the transfer case gearing over axle gearing personally. This transmission has changed the game. Here's an easy perspective if you had a non-rubicon TJ. Remember the doubler kits they sold back in the day to add a 2nd range box in front of the 231? Even with 2x2.72 low range and 4.10s to retain freeway driveability, that crap trans would leave you with...an 86-1 crawl ratio. With a doubler you'd get a stock XR crawl ratio and still have worse freeway gears. Tell me again I need more gearing? I guarantee the JLUR outcrawls the TJ, 0-60s in half the time, and will roll 85mph without straining and returning double the fuel economy. These aren't the Jeeps of yesterday by a long shot.

We definitely have different opinions on this.

I'd rather be spinning 2,500 RPM on the highway because these low HP 3.6L V6 motors do not like lugging at 2,000 RPM. They can't do it when the OD reduction is 0.67 unless going downhill or with a tail wind. Now a 400 HP V8, sure, those will cruise at 2,000 RPM on the highway all day long and be happy.

The first gear ratio of a JT compared to anything else is not relevant to me. I'm not regearing for the benefit in first gear. I'm not in first gear that often. If I were to regear mine, it would be to be able to cruise in overdrive on the highway. Currently with 3.73 and 35s, mine wants to run around in 6th gear most often. I basically turned my 8 speed into a 6 speed when I slapped 35s on and didn't regear.

 

[Zachanadandy]

We definitely have different opinions on this.

I'd rather be spinning 2,500 RPM on the highway because these low HP 3.6L V6 motors do not like lugging at 2,000 RPM. They can't do it when the OD reduction is 0.67 unless going downhill or with a tail wind. Now a 400 HP V8, sure, those will cruise at 2,000 RPM on the highway all day long and be happy.

The first gear ratio of a JT compared to anything else is not relevant to me. I'm not regearing for the benefit in first gear. I'm not in first gear that often. If I were to regear mine, it would be to be able to cruise in overdrive on the highway. Currently with 3.73 and 35s, mine wants to run around in 6th gear most often. I basically turned my 8 speed into a 6 speed when I slapped 35s on and didn't regear.

My JTM cruises in 7th under moderate loads with the factory 4.10s and 37s, which is still overdrive. It sees 8th regularly under light loads, which don't cause any lugging because they are light loads. 2100rpms at 85mph just like a stock JL sport or sahara. If it was over geared to the point of lugging do you really think fca would sell and warrant tens of thousands of them that way?

 

[Wheelin98TJ]

My JTM cruises in 7th under moderate loads with the factory 4.10s and 37s, which is still overdrive. It sees 8th regularly under light loads, which don't cause any lugging because they are light loads. 2100rpms at 85mph just like a stock JL sport or sahara. If it was over geared to the point of lugging do you really think fca would sell and warrant tens of thousands of them that way?

FCA doesn't sell them with 37s/4.10 or 35s/3.73.

 

[hjdca]

Just bought a new to me 22 Gladiator Sport (3.73).
Went from the OEM tires to 33" BFGs and wondering if I should go to 4.30 or 4.56?
Even though it rides and drives OK, its a bit sluggish and shifts back n forth between 7th and 8th gear at regular highway speed (60mph).
Its a weekend back-roader and doubt it will see too much off-roading... Not too concerned with mpg because its not my daily driver but also don't want everything spinning unnecessarily fast if not needed.

Put it this way.... My Rubicon came with 4:10s and 33 inch tires... It was still geared too high from the factory because of mpg considerations I guess. I live in the So Cal mountain area. IMHO, it should have come from the factory with 4:56 gears... If you are going to spend the money for a gear change, go at least 4:88s and the next go around get 35 inch tires. I believe 4:88s are perfect for 35 inch tires... I like my 5:13s for my 37 inch tires, but, like I said, I live in a mountainous area and I am also sure I would have been happy if I went with 5:38s instead... Also, I have never heard anybody say, "I went too low on my gear change".... It is always the other way around.

Note: I also like Dana Spicer for the gears... You never hear of problems with them.

 

[Heavy D]

Put it this way.... My Rubicon came with 4:10s and 33 inch tires... It was still geared too high from the factory because of mpg considerations I guess. I live in the So Cal mountain area. IMHO, it should have come from the factory with 4:56 gears... If you are going to spend the money for a gear change, go at least 4:88s and the next go around get 35 inch tires. I believe 4:88s are perfect for 35 inch tires... I like 5:13s for 37 inch tires, but, like I said, I live in a mountainous area.

Note: I also like Dana Spicer for the gears... You never hear of problems with them.

I went with the Dana Spicer's... I'm only 400 miles into swap so don't have an opinion on em yet.

Also I went with the 4.56 because I'm putting on 35s as soon as I figure out how much & which lift to go with and wanted to end up with what I feel will be the equivalent of 4.10 ratio with the aftermarkets installed.

My JT is a weekend road-tripper and will likely never be off-roaded.
I also want my JT to utilize 8th gear when I'm at highway speed and not just occasionally under ideal conditions.

 

[Zachanadandy]

FCA doesn't sell them with 37s/4.10 or 35s/3.73.

The jl comes with 3.45s and 32s stock which equates to 4.00 gears with 37s, add the extra .1 for rolling resistance and viola my jt is geared exactly like a factory Jeep...

 

[Wheelin98TJ]

The jl comes with 3.45s and 32s stock which equates to 4.00 gears with 37s, add the extra .1 for rolling resistance and viola my jt is geared exactly like a factory Jeep...

JLs also come with 4.10 and 33s. Your JL XR had 4.56 and 35s. You think Jeep would still use 4.10 for 37" tires?

 

[WILDHOBO]

My JTM cruises in 7th under moderate loads with the factory 4.10s and 37s, which is still overdrive. It sees 8th regularly under light loads, which don't cause any lugging because they are light loads. 2100rpms at 85mph just like a stock JL sport or sahara. If it was over geared to the point of lugging do you really think fca would sell and warrant tens of thousands of them that way?

They definitely would. They geared them the way they do to increase fuel economy.

 

[Zachanadandy]

They definitely would. They geared them the way they do to increase fuel economy.

Lugging and subsequent engine failure is not economical (not that you're lugging the engine at 2k rpms and low load either but you seem convinced that's the case). They are geared that way for fuel economy because 2k rpms is more efficient than 2500 especially under light loads. If you let the automatic do its job you'll never lug the engine. The load goes up, downshift. Load goes down, upshift. That's how it's supposed to work. It was never intended to be geared so low it would hold 8th under moderate to heavy loads. That defeats the purpose of having 2 overdrives and 8 gears.

 

[ShadowsPapa]

Lugging and subsequent engine failure is not economical (not that you're lugging the engine at 2k rpms and low load either but you seem convinced that's the case). They are geared that way for fuel economy because 2k rpms is more efficient than 2500 especially under light loads. If you let the automatic do its job you'll never lug the engine. The load goes up, downshift. Load goes down, upshift. That's how it's supposed to work. It was never intended to be geared so low it would hold 8th under moderate to heavy loads. That defeats the purpose of having 2 overdrives and 8 gears.

You won't necessarily lug it because it will downshift. I'd have to really seriously try to get mine to the point of "lugging".
These things monitor a whole lot more than just road speed vs. engine RPM.

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